1. Field of the Invention
The present invention relates to a solid-state image pickup apparatus in which a light receiving portion is hermetically sealed, and a method for manufacturing the same.
2. Description of the Related Art
The applicant has proposed a solid-state image pickup apparatus, in which a light receiving portion is hermetically sealed, having a novel structure particularly having a small shape after mounting to allow application to a field requiring small size mounting. FIG. 1 and FIG. 2 are cross-sectional explanatory view showing schematic structures of publicly known solid-state image pickup apparatuses already proposed by the applicant.
For example, the applicant has proposed a solid-state image pickup apparatus 110, in which a hermetic seal portion 109 is provided only in a light receiving area 124 of a solid-state image pickup device chip 120, shown in FIG. 1 in Japanese Patent Application Laid-Open Publication No. 7-202152. In the solid-state image pickup apparatus 110, a seal member 127 forming the hermetic seal portion 109 is composed of two members of a flat plate portion 127A made of a transparent member, and a frame portion 127B. It is described that the frame portion 127B of the seal member 127 may be formed using an inorganic substance, such as ceramic, glass, or silicon, or a metal, such as Kovar or alloy 42, but that a resin, such as an epoxy, phenol, or silicon resin, may be pattern formed on a surface of the solid-state image pickup device chip 120 by printing or a photolithography technique, and that the seal member 127, in which the frame portion 127B is adhered to the flat plate portion 127A, may be adhered to the surface of the solid-state image pickup device chip 120.
Also, the applicant has proposed a solid-state image pickup apparatus 210 shown in FIG. 2 in Japanese Patent No. 3880278. The solid-state image pickup apparatus 210 has a structure in which a solid-state image pickup device chip 220 having a light receiving portion 224 in which a microlens 221 is formed, an adhesive layer 230A, an epoxy-based resin sheet 226 having a perforated portion only in the light receiving portion 224, an adhesive layer 230B, and a flat plate portion 227 made of a transparent member are laminated and adhered. In other words, in the solid-state image pickup apparatus 210, a hermetic seal portion 209 is formed by a frame portion 231 including the resin sheet 226, the adhesive layer 230A, and the adhesive layer 230B, and the flat plate portion 227. Here, it is described that as a material of the flat plate portion 227, glass, quartz, sapphire, a transparent resin, or the like is suitable, and that as the adhesive layer 230A or 230B, an epoxy-based or silicon-based resin adhesive is suitable.
For leading out an electrode line from a pad electrode portion, not shown, formed on a periphery of a surface of the solid-state image pickup device chip 220, the solid-state image pickup apparatus 210 has a pad portion wiring 225A electrically connected to the pad electrode portion, a chip side wiring 225B, and a chip back wiring 225C, and the chip back wiring 225C is further electrically connected to a back pad electrode portion not shown. The solid-state image pickup apparatus 210 can be electrically connected to a mounting substrate or the like from the back pad electrode portion via a bump or the like.
In the solid-state image pickup apparatus 110 and the solid-state image pickup apparatus 210, small size mounting is possible, and particularly, even if an optical component, such as a filter, a microlens, or a prism, is formed on a surface of the solid-state image pickup device chip, an optical capability of the optical component does not decrease.
However, in the solid-state image pickup apparatus 210, the frame portion 231 forming the hermetic seal portion 209 has the resin sheet 226 and the resin adhesive layers 230A and 230B as components. It is not easy to precisely control a thickness of the resin adhesive layer or the like, so that a height of the frame portion 231, that is, a distance between the flat plate portion 227 and the surface of the solid-state image pickup device chip 220, may fluctuate. The distance between the flat plate portion 227 and the surface of the solid-state image pickup device chip 220 may cause an optical interference effect, depending on the distance. Therefore, if the distance between the flat plate portion 227 and the surface of the solid-state image pickup device chip 220 fluctuates between lots, fluctuations in optical properties of the microlens or the like, that is, fluctuations in image pickup properties of the solid-state image pickup apparatus 210, may occur between lots.
Also, in the solid-state image pickup apparatus 210 using a resin as a component of a seal member forming the hermetic seal portion 209, moisture resistance and durability properties, that is, reliability, may not be sufficient. Also, the chip side wiring 225B for leading out the electrode line of the solid-state image pickup apparatus 210 is formed after solid-state image pickup device chips are separated into individual pieces from a wafer, so that a manufacturing process is complicated.
Similarly, in the solid-state image pickup apparatus 110, the frame portion 127B formed separately is adhered to the flat plate portion 127A, which is adhered to the surface of the solid-state image pickup device chip 120. Therefore, in the solid-state image pickup apparatus 110, it is not easy to always control a height of the frame portion 127B, that is, a distance between the flat plate portion 127A and the surface of the solid-state image pickup device chip 120, at a constant level. Therefore, for the solid-state image pickup apparatus 110, fluctuations in optical properties of the microlens or the like, that is, fluctuations in image pickup properties between lots, may occur.
Also, the frame portion forming the hermetic seal portion in the solid-state image pickup apparatus 110 and the solid-state image pickup apparatus 210 is a member only for forming the hermetic seal portion.
As described above, in conventional solid-state image pickup apparatuses, importance of forming the hermetic seal portion, addressing small size mounting, and the like is recognized, but it cannot be said that sufficient attention is paid to a material of the seal member for forming the hermetic seal portion, a method for forming the hermetic seal portion, and protection of a region other than the light receiving area.